Suppression of a single BAHD gene in Setaria viridis causes large, stable decreases in cell wall feruloylation and increases biomass digestibility

Abstract

Summary Feruloylation of arabinoxylan (AX) in grass cell walls is a key determinant of recalcitrance to enzyme attack, making it a target for improvement of grass crops, and of interest in grass evolution. Definitive evidence on the genes responsible is lacking so we studied a candidate gene that we identified within the BAHD acyl‐CoA transferase family.We used RNA interference (RNAi) silencing of orthologs in the model grasses Setaria viridis (SvBAHD01) and Brachypodium distachyon (BdBAHD01) and determined effects on AX feruloylation.Silencing of SvBAHD01 in Setaria resulted in a c. 60% decrease in AX feruloylation in stems consistently across four generations. Silencing of BdBAHD01 in Brachypodium stems decreased feruloylation much less, possibly due to higher expression of functionally redundant genes. Setaria SvBAHD01 RNAi plants showed: no decrease in total lignin, approximately doubled arabinose acylated by p‐coumarate, changes in two‐dimensional NMR spectra of unfractionated cell walls consistent with biochemical estimates, no effect on total biomass production and an increase in biomass saccharification efficiency of 40–60%.We provide the first strong evidence for a key role of the BAHD01 gene in AX feruloylation and demonstrate that it is a promising target for improvement of grass crops for biofuel, biorefining and animal nutrition applications.

Response of cell-wall composition and RNA-seq transcriptome to methyl-jasmonate in Brachypodium distachyon callus

“…This contrasts with markedly differing responses of different diFA dimers to suppression of SvBAHD01 gene Setaria viridis (de Souza et al 2018). …”

Downregulation of p‐COUMAROYL ESTER 3‐HYDROXYLASE in rice leads to altered cell wall structures and improves biomass saccharification

“…First, as mentioned above, the reductions in wall‐cross‐linking FAs should positively affect the saccharification of C3′H ‐KD rice cell walls, logically by reducing interactions between polysaccharides and lignins. In fact, previous studies with artificial cell wall models (Grabber et al ., ,b, ) and with plants harboring various levels of FA (Lam et al ., ; Piston et al ., ; Buanafina et al ., ; Reem et al ., ; de Souza et al ., ) have shown negative correlations between the abundance of wall‐bound FAs and the degradability of grass cell walls. On the other hand, enriched H lignins themselves might also affect cell wall recalcitrance.…”

Designing xylan for improved sustainable biofuel production

“…Further examination of AX feruloylation (de Souza et al ., ) identified a member of the BAHD acyltransferase family involved in the transference of FA residues to the AX backbone. Silencing the SvBAHD01 gene by RNAi in Setaria viridis reduced FA content by 60% and increased stem saccharification efficiency (from 40 to 60%), without changing biomass productivity.…”